This dissertation is about the role of objects in social life, specifically, in the social interactions that create identity. I take a close look at the experiences of people who use prosthetic legs to delve into the details of how technological objects and bodies participate in these interactions. I argue that objects and bodies contribute to human identities and take on their own kind of object- identity in the process. This analysis also reveals changes in popular attitudes toward amputation and prosthetic technology over the last three decades. I suggest that these changes reflect wider shifts in the meaning of bodies and disability in the U.S. These changes highlight a weakness in theories of identity as a basis for inequality that is focused on stigma and deviation from cultural norms. Instead of describing norms and identities as relatively static or as arising from interactions among humans, my approach bases identity in interactions between humans and objects (including bodies), thereby accounting for the role of materiality in the construction of social identity without resorting to technological or biological determinism. Prosthetic limbs are a particularly good case to study when sorting out the role of the body in social identity. Prosthetic legs replace lost legs aesthetically and functionally, but also require daily management. These obvious and intimate interactions between humans and devices are an occasion to see how self, technology, and body relate. By taking seriously the roles of humans and non-humans, my analysis keeps sight of the ways interacting with one's own body takes work